That's a professional job for mine. I do most of my own repairs, but if you want any modicum of cosmetic niceties, then take it to a professional. Avoidance is easier than repair. If you are buying new boards then get a custom with extra glass; unless you are an uber shredder, you aren't good enough to notice the difference in performance that extra glass makes. Get a 6/4 oz deck as minimum. Anything else is treating surfboards as disposable. Which is okay. But don't expect longevity from a rack brought board that is single 4 or double 4 oz glass. They are designed for you to be buying new boards regularly.
A little extra glass doesn't feel as sexy under the arm, but for the vast majority of recreational surfers it makes sweet FA difference to the way they surf.
And I guess the original post is about how to repair it:
Clean it off, sand it back and start filling it with layers of glass until it is level with the stringer. You probably will need to do this incrementally with two layers of glass, let it cure, then another two layers of glass. This let of the repair is to build it up, so don't lap over the stringer. You are looking to fill in the hole, so even half the width where it is deepest for the first layer, then slightly larger for the second. The final layer is the actual patch that needs to cover the whole damaged area by at least an inch. Then sand it back. It's going to take three or four days of glassing, curing, sanding, glassing...to get it back.
For noses and tail repairs, to get the shape back, it has taken me up to 5 layers. It's a lot of sanding, but the secret is patience.
I don't know if you have any practical skills, so sorry if his is stating the obvious, but scrape as much wax off as possible, then remove the residual wax with turps, then remove the oily residue with metho before commencing the repair.
Me? For a new board and such a big ding, I would wanted it looking good and my repairs work but are generally pretty ugly. Take it to a professional.
1. Remove all wax around said area, plus a bit extra. 2. Remove all cracked Fibreglass with a knife ( anything that is not flush with board deck.) 3. Lay board out in sun to dry out the foam, or use hair dryer. Shouldn't take long. 3. Buy good quality tape. Maybe high temperature tape ( 3m green colour from Bunnings ) Make a bund around open ding area with tape. 3. Purchase 1lt Laminating resin, some left over to keep for future repairs ( Hoping its a PU Blank not EPS ) also 500ml of Filler resin. 4. Purchase Small Catalyst. Rule of thumb, starting point. 1% to whatever Lam in ML you use. e.g. 150ml of Lam use 1.5ml of catalyst. This would be for a average to warm day. Cooler day boost up your %. Add the catalyst as last ingredient. 5. Buy some Qcell. Mix this into your Lam resin. Small amount build up to gooey consistency. 6. Buy some white pigment to add to Lam Qcell mix. Mix small amount in to get that solid white colour. 7. Now you have added Catalyst as last ingredient . Pour into ding so it sits above the board deck height. 8. Once set sand back with 120 grit sandpaper ( Blue Paper ) Now it's flush with the deck sand lightly about a inch past the ding all around. 9. Buy some 6 oz fiberglass cloth to go over the ding. Lay over the ding. Now back to the Lam resin mix up a small amount again. No Qcell or Pigment, just catalyst. Wet this out with a small throw away brush. 10. Once set. You now need to lightly scrape away high points with a razor blade edge. ( Saves sanding time later. ) 11. Now mix up catalyst with your filler resin ( same ratios )now with another throw away brush paint over the repair you have done. 12. Once set. Sand with 120 grit , careful not to go through the fiberglass weave then 240 grit. 13. As it's the deck can leave at that or purchase a spray can of Satin or flat acrylic lacquer to spray over. 14. Now go surfing....
I have done something very similar to a new board, courtesy of a badly timed air and errant knee. I annihilated the stringer as well so count yourself lucky! I never even considered not going to a pro repairer. Ross @ Soul Boardstore in Scarborough fixed it up a treat!